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* Copyright (c) 2008, Whiteboard-IT
* All rights reserved.
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* Redistributions of source code must retain the above copyright notice, this list of conditions and the following 
 * disclaimer.
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 * disclaimer in the documentation and/or other materials provided with the distribution.
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using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Linq;

namespace Mite
{
	public class Query : IDisposable
	{
		protected Query(Table table, IDbConnection connection)
		{
			_table = table;
			_connection = connection;
		}

		#region IDisposable Members

		public void Dispose()
		{
		}

		#endregion

		public static Query For(Table table, IDbConnection connection)
		{
			Guard.ArgumentNotNull("table", table);
			Guard.ArgumentNotNull("connection", connection);
			return new Query(table, connection);
		}

		public Query Select(params Column[] columns)
		{
			columns.ForEach(column => _columns.Add(column));
			return this;
		}

		public Query Where(string condition)
		{
			_where = condition;
			return this;
		}

		public T ExecuteScalar<T>()
		{
			using (var conn = IoC.Resolve<IDbConnection>())
			{
				using (IDbCommand cmd = conn.CreateCommand())
				{
					cmd.CommandText = GetCommandText();
					object o = cmd.ExecuteScalar();
					return (T) o;
				}
			}
		}

		private string GetCommandText()
		{
			string cmdText = string.Format("SELECT {0}", String.Join(", ", (from column in _columns
			                                                                select column.Name).ToArray()));
			if (!String.IsNullOrEmpty(_where))
				cmdText += String.Format(" WHERE {0}", _where);

			cmdText += String.Format(" FROM {0}", _table.Name);

			return cmdText;
		}

		public IDictionary<Column, ArrayList> ExecuteReader()
		{
			using (IDbConnection conn = GetConnection())
			{
				if (conn.State !=
				    ConnectionState.Open)
					conn.Open();

				using (IDbCommand cmd = conn.CreateCommand())
				{
					cmd.CommandText = GetCommandText();
					IDataReader dr = cmd.ExecuteReader();
					var dict = new Dictionary<Column, ArrayList>();
					_columns.ForEach(column => dict.Add(column, new ArrayList()));
					while (dr.Read())
					{
						_columns.ForEach(column =>
						                 {
						                 	object value = dr[column.Name];
						                 	dict[column].Add(value);
						                 });
					}
					return dict;
				}
			}
		}

		protected IDbConnection GetConnection()
		{
			return _connection;
		}

		private readonly IList<Column> _columns = new List<Column>();
		private readonly IDbConnection _connection;
		private readonly Table _table;
		private string _where;
	}
}